Hi, Hujok.
등업 is a kind of internet slang, a noun, a shorten word of 등급(level)업(up from the english word up).
It means 'promotion on an internet group'
Examples;
등업 부탁드려요.
please elevate me to the higher level.
등업 신청.
an application for a higher level.
등업하는 법.
How to get into a higher level.
If you get into a higher level in a group on the internet(we often call it as 'Cafe'),
you can get more advantages such as; you can see more information; you get the right to post something on some specific message boards.